Electric field grading protection design surrounding a galvanic or capacitive isolator

ABSTRACT

Micro-isolators exhibiting enhanced isolation breakdown voltage are described. The micro-isolators may include an electrically floating ring surrounding one of the isolator elements of the micro-isolator. The isolator elements may be capacitor plates or coils. The electrically floating ring surrounding one of the isolator elements may reduce the electric field at the outer edge of the isolator element, thereby enhancing the isolation breakdown voltage.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.16/887,719, filed May 29, 2020 and entitled “ELECTRIC FIELD GRADINGPROTECTION DESIGN SURROUNDING A GALVANIC OR CAPACITIVE ISOLATOR,” whichis hereby incorporated by reference herein in its entirety.

FIELD OF THE DISCLOSURE

The present application relates to isolators providing galvanicisolation between circuits.

BACKGROUND

Isolators provide electrical isolation between circuits whichcommunicate with each other. In some situations, circuits whichcommunicate with each other operate at different voltages, for instanceone at a relatively high voltage and the other at a relatively lowvoltage. In some situations, the circuits may or may not operate atdifferent voltages than each other, but are referenced to differentelectrical ground potentials. Isolators can be used to electricallyisolate circuits in either of these situations.

BRIEF SUMMARY

According to an aspect of the present application, micro-isolatorsexhibiting enhanced isolation breakdown voltage are described. Themicro-isolators may include an electrically floating ring surroundingone of the isolator elements of the micro-isolator. The isolatorelements may be capacitor plates or coils. The electrically floatingring surrounding one of the isolator elements may reduce the electricfield at the outer edge of the isolator element, thereby enhancing theisolation breakdown voltage.

According to some embodiments, a micro-isolator with enhanced isolationbreakdown voltage is provided, comprising: a first isolator element in afirst plane; a second isolator element in a second plane; a firstdielectric material, comprising a polymer, disposed between the firstand second isolator elements; and an electrically floating ring disposedin the first plane and surrounding the first isolator element.

According to some embodiments, a micro-isolator with enhanced isolationbreakdown voltage, comprising: first and second isolator elementsdisposed in respective planes; a dielectric material, comprising apolymer, disposed between the first and second isolator elements; and anelectrically floating ring in-plane with and surrounding the firstisolator element.

According to some embodiments, an isolated system, comprising: a firstdevice configured to operate in a first voltage domain; a second deviceconfigured to operate in a second voltage domain; an isolator coupledbetween the first device and second device and comprising anelectrically floating ring surrounding a first isolator element of apair of vertically separated isolator elements.

BRIEF DESCRIPTION OF DRAWINGS

Various aspects and embodiments of the application will be describedwith reference to the following figures. It should be appreciated thatthe figures are not necessarily drawn to scale. Items appearing inmultiple figures are indicated by the same reference number in all thefigures in which they appear.

FIG. 1A illustrates a cross-sectional view of a micro-isolator havingtwo isolator elements with a floating conductive ring around one,according to a non-limiting embodiment of the present application.

FIG. 1B is a top view of the micro-isolator of FIG. 1A taken along theline 1B-1B of FIG. 1A.

FIG. 2 illustrates an alternative micro-isolator according to anon-limiting embodiment.

FIG. 3 illustrates a cross-sectional view of an alternativemicro-isolator comprising multiple floating conductive rings, accordingto a non-limiting embodiment of the present application.

FIG. 4 illustrates a cross-sectional view of an alternativemicro-isolator in which the floating conductive ring is not encapsulatedby the same non-linear dielectric material encapsulating the isolatorelement 104 a, according to an alternative embodiment.

FIG. 5 illustrates a cross-sectional view of an alternativemicro-isolator in which the non-linear dielectric material filling thegap between the isolator element and the floating conductive coil is adifferent material than that encapsulating the isolator element,according to a non-limiting embodiment of the present application.

FIG. 6 illustrates a cross-sectional view of an alternativemicro-isolator in which the floating conductive ring surrounding theisolator element has a different height than the isolator element,according to a non-limiting embodiment of the present application.

FIG. 7 illustrates a top view of a micro-isolator having a serpentineisolator element surrounded by a plurality of floating conductive rings,according to a non-limiting embodiment of the present application.

FIG. 8 illustrates a top view of a micro-isolator having a segmentedfloating conductive ring surrounding an isolator element, according to anon-limiting embodiment of the present application.

FIG. 9 illustrates a cross-sectional view of a micro-isolator havingfloating conductive rings surrounding both the top and bottom isolatorelements, according to a non-limiting embodiment of the presentapplication.

FIG. 10 is a block diagram illustrating an example of a systemcomprising an isolator of the types described herein.

DETAILED DESCRIPTION

According to an aspect of the present application, an isolator elementis positioned within an electrically floating conductive ring, with anon-linear dielectric material between them. In some embodiments, theisolator element is a coil, and in other embodiments it is a capacitorplate. In some embodiments, the isolator element and electricallyfloating conductive ring are both encapsulated by a dielectric material,which in some embodiments may be the same non-linear dielectric materialbetween the isolator element and the electrically floating conductivering. In some embodiments, the isolator element is encapsulated by thenon-linear dielectric material while the electrically floatingconductive ring is not. In some embodiments, the isolator element isencapsulated by a dielectric material differing from the non-lineardielectric material between the isolator element and the electricallyfloating conductive ring. According to some embodiments, multipleelectrically floating conductive rings may surround the isolatorelement. They may be the same height as the isolator element or adifferent height. In some embodiments, an isolator comprising twoisolator elements includes one or more electrically floating conductiverings around each of the isolator elements.

The aspects and embodiments described above, as well as additionalaspects and embodiments, are described further below. These aspectsand/or embodiments may be used individually, all together, or in anycombination of two or more, as the application is not limited in thisrespect.

FIG. 1A illustrates a cross-sectional view of a micro-isolator havingtwo isolator elements with a floating conductive ring around one. Themicro-isolator 100 comprises a substrate 102, first isolator element 104a, second isolator element 104 b, floating conductive ring 106,dielectric layer 108, non-linear dielectric 110, and dielectric layer112.

The first isolator element 104 a and second isolator element 104 b arecoils in this non-limiting example. The micro-isolator 100 may thereforework as an inductive micro-isolator, and may be a transformer. The firstisolator element 104 a and second isolator element 104 b may be made ofa metal, such as gold, aluminum, or copper. In some embodiments, thefirst isolator element 104 a and second isolator element 104 are made ofdifferent materials. For example, isolator element 104 a may be made ofgold and isolator element 104 b may be made of aluminum. In someembodiments, they may be made of the same material, such as being madeof the same metal.

The floating conductive ring 106 may be made of a metal. In someembodiments, the floating conductive ring 106 may be made of the samemetal as the first isolator element 104 a. For example, they may bepatterned from the same metal layer, although not all embodiments arelimited in this respect. The first isolator element 104 a and thefloating ring 106 may be made of gold. The first isolator element 104 aand floating conductive ring 106 have a height H. In this non-limitingembodiment, they have the same height, although alternatives arepossible, with an example described further below. Electrical contactmay be made to first isolator element 104 a at its ends, as can be seenin FIG. 1B.

FIG. 1B is a top view of the micro-isolator 100 taken along the line1B-1B of FIG. 1A. As shown, the floating conductive ring 106 surroundsthe first isolator element 104 a. The floating conductive ring isconcentrically outside the first isolator element 104 a. Electricalcontact to the first isolator element 104 a is made at pad 114 and end116 (which may be a separate pad). The first isolator element 104 a maypass over or under the floating conductive ring 106 near the end 116 toavoid being in electrical contact. In an alternative embodiment,floating conductive ring 106 may include a break or gap near the end 116through which the first isolator element 104 a passes. In someembodiments, the first isolator element 104 a may be configured toreceive a high voltage, such as greater than 200 Volts, greater than 500Volts, greater than 1000 Volts, between 500 V and 3.5 kV, or any rangeor values within those ranges.

The first isolator element 104 a and floating conductive ring 106 mayhave any suitable shapes. In the non-limiting example of FIG. 1B, theyare circular. Alternative shapes are possible, however, as the variousaspects described herein are not limited to a particular shape ofisolator element or the floating conductive ring.

Returning to FIG. 1A, the dielectric layer 108 may be any suitabledielectric for isolating the first isolator element 104 a from thesecond isolator element 104 b. In some embodiments, the dielectric layer108 comprises a polymer. For example, it may be polyimide. In someembodiments, the dielectric layer may comprise multiple layers. Forexample, the dielectric layer 108 may comprise two or more layers ofpolyimide, or a layer of polyimide and a layer of a second type ofdielectric.

The first isolator element 104 a and the floating conductive ring 106are separated in-plane by a gap g. The gap g may have any suitabledistance. The floating conductive ring 106 serves to reduce the electricfield buildup at the outer edge of the first isolator element 104 a, andmay perform a grading function of smoothing the voltage between thefirst isolator element 104 a and surrounding structures. As a result,the breakdown voltage of the micro-isolator 100 is increased compared toif the floating conductive ring 106 was omitted. The value of g may beselected to provide a desired level of electric field reduction. If g istoo great, the floating conductive ring 106 may not meaningfully reducethe electric field at the outermost edge of the first isolator element104 a. If g is too small, electrical breakdown may occur between thefirst isolator element 104 a and the floating conductive ring 106. Insome embodiments, g may be in a range from 0.5 microns to 10 microns,including any value within that range. Other values are also possible.

The gap g is filled with the non-linear dielectric 110. The non-lineardielectric 110 may be a relatively conductive insulator to aid theelectric field grading function of the floating conductive ring 106. Insome embodiments, the non-linear dielectric 110 is stoichiometricsilicon nitride (SiN_(1.33)) or non-stochiometric silicon nitride(SiN_(x), with x not equal to 1.33). Alternatives include siliconoxynitride (SiONx), doped amorphous silicon (a-Si:H), doped amorphouscarbon (a-C:H), silicon carbide (SiC), and zinc oxide (ZnO). When dopedmaterials are used, any suitable doping may be employed to provide alevel of conductivity resulting in a desired level of electric fieldgrading. In some embodiments, the non-linear dielectric 100 may be ahigh-k ferroelectric materials like baryum titanate (BaTiO₃) strontiumtitanate (SrTiO₃), titanate dioxide (TiO₂), hafnium dioxide (HfO₂),zirconium dioxide (ZrO₂) or alumina (Al₂O₃), as they may exhibit similarelectric field grading behavior. It should be noted that including afloating conductive ring in an isolator, without a non-linear dielectricbetween the first isolator element and the floating conductive ring, candecrease the electric breakdown voltage of the isolator, rather thandecreasing it. Thus, the combination of a floating conductive ring witha conductive non-linear dielectric material between the isolator elementand the floating conductive ring may provide the desired increase inelectric breakdown voltage.

The dielectric layer 112 may be a passivation layer. In someembodiments, the dielectric layer 112 is polyimide. In some embodiments,the dielectric layer 112 is an oxide. Alternative materials are possiblefor the dielectric layer 112.

A non-limiting example of an implementation of the micro-isolator 100 isnow provided. The substrate 102 may be formed of silicon or a dielectric(such as glass). The first isolator element 104 a may be formed of gold.The second isolator element 104 b may be formed of aluminum. Thefloating conductive ring 106 may be formed of gold. Alternative isolatorelements 104 a and 104 b as well as the floating conductive ring 106 maybe formed of copper. The dielectric layer 108 may be formed of polyimideand may be between 50 microns and 200 microns thick. The non-lineardielectric 110 may be formed of silicon nitride. The dielectric layer112 may be formed of oxide. The height H may be 10 microns and the gap gmay be 1 micron. Other materials and dimensions may be used in otherembodiments. Also, it should be appreciated that some embodiments of amicro-isolator as described herein include one or more of the elementsformed of the specific materials just described, but that one or more ofthe elements may be formed of different materials.

It should be appreciated from FIGS. 1A and 1B that in some embodiments amicro-isolator with enhanced isolation breakdown voltage is provided.The micro-isolator may comprise a first isolator element in a firstplane, a second isolator element in a second plane, a first dielectricmaterial, comprising a polymer such as polyimide, disposed between thefirst and second isolator elements, and an electrically floatingconductive ring disposed in the first plane and surrounding the firstisolator element. The first and second isolator elements may beseparated in a vertical dimension (the up and down direction of FIG.1A), and the first isolator element and floating conductive ring may beseparated in a second dimension (the left-right direction in FIG. 1A).

FIG. 2 illustrates an alternative micro-isolator according to anon-limiting embodiment. The micro-isolator 200 differs from themicro-isolator 100 in that the micro-isolator 200 is a capacitivemicro-isolator, having capacitor plates as the isolator elements.Specifically, the micro-isolator 200 comprises substrate 102, firstisolator element 204 a, second isolator element 204 b, floatingconductive ring 206, dielectric layer 108, non-linear dielectric 110,and dielectric layer 112. Substrate 102, dielectric layer 108,non-linear dielectric 110, dielectric layer 112, gap g, and height Hwere previously described in connection with FIG. 1A, and thus are notdescribed in detail again here.

The first isolator element 204 a and second isolator element 204 b arecapacitor plates. They may be formed of any suitable materials, such asthe materials described previously in connection with first isolatorelement 104 a and second isolator element 104 b, respectively. Theisolator elements 204 a and 204 b may have any suitable shapes. In someembodiments, they are circular, in other embodiments rectangular orsquare, and in still other embodiments may have different shapes. Thefloating conductive ring 206 may surround the first isolator element 204a. In some embodiments, the floating conductive ring 206 has the sameshape as the first isolator element 204 a, for example being a circle, asquare, or other suitable shape. The floating conductive ring 206 may bemade of any of the materials described previously in connection withfloating conductive ring 106.

FIG. 3 illustrates a cross-sectional view of an alternativemicro-isolator comprising multiple floating conductive rings, accordingto a non-limiting embodiment of the present application. Themicro-isolator 300 comprises substrate 102, first isolator element 104a, second isolator element 104 b, floating conductive rings 306 a, 306 b. . . 306 n, dielectric layer 108, non-linear dielectric 110, anddielectric layer 112. The substrate 102, first isolator element 104 a,second isolator element 104 b, dielectric layer 108, non-lineardielectric 110, and dielectric layer 112 have been described previouslyherein in connection with FIGS. 1A and 1B, and therefore are notdescribed again in detail here.

The floating conductive rings 306 a, 306 b . . . 306 n may be anysuitable floating conductive rings. Each of them may be substantiallythe same as the floating conductive ring 106 described previously inconnection with FIGS. 1A and 1B, in terms of material and sizing. Thefloating conductive rings 306 a, 306 b . . . 306 n have different radii(in the xy-plane), with floating conductive ring 306 a having a shorterradius than floating conductive ring 306 b, which in turn has a shorterradius than floating conductive ring 306 n. The floating conductiverings 306 a . . . 306 b may be concentrically positioned with respect toeach other.

Any suitable number n of floating conductive rings may be provided. Inthe embodiment of FIG. 3 , between two and ten floating conductive ringsmay be provided. However, other numbers are possible.

The floating conductive rings 306 a . . . 306 n may be the same in termsof material, spacing, height, and width in some embodiments. However, inthose embodiments in which multiple floating conductive rings areprovided, one or more of those variables may be varied among thefloating conductive rings. For example, in some embodiments, two or moreof the floating conductive rings 306 a . . . 306 n may differ in height(in the z-direction in this figure). For example, some of the floatingconductive rings may have the height H described previously, whileothers may have a shorter height, such as is described further below inconnection with FIG. 6 . Any suitable gaps may be provided between thefloating conductive rings, as shown. The gap g1 is between the outermostedge of the first isolator element 104 a and the floating conductivering 306 a. The gap g2 is between the floating conductive ring 306 a andthe floating conductive ring 306 b. In some embodiments, the gapsincrease in size the further from the first isolator element 104 a theyare. That is, the gap sizing may increase moving away from the firstisolator element 104 a. Increasing the gap size may increase theresistance between the floating conductive rings, which may facilitateelectric field grading. The floating conductive rings may have widths w.In some embodiments, they have a uniform width. In other embodiments,the widths may be varied among the floating conductive rings 306 a . . .306 n.

FIG. 4 illustrates a cross-sectional view of an alternativemicro-isolator in which the floating conductive ring is not encapsulatedby the same non-linear dielectric material encapsulating the isolatorelement 104 a, according to an alternative embodiment. Themicro-isolator 400 includes many of the same components previouslydescribed in connection with FIGS. 1A and 1B. However, in contrast tothe micro-isolator 100 of FIG. 1 , the micro-isolator 400 is configuredsuch that the non-linear dielectric 110 does not encapsulate thefloating conductive ring 106. Such a configuration may be used for anysuitable purpose. In some embodiments, manufacturing of themicro-isolator may be eased by forming the floating conductive ring 106without being encapsulated by the non-linear dielectric 110. Otherbenefits may also be realized.

FIG. 5 illustrates a cross-sectional view of an alternativemicro-isolator in which the non-linear dielectric material filling thegap between the isolator element and the floating conductive ring is adifferent material than that encapsulating the isolator element,according to a non-limiting embodiment of the present application. Themicro-isolator 500 comprises substrate 102, first isolator element 104a, second isolator element 104 b, floating conductive ring 106,dielectric layer 108, non-linear dielectric 110, dielectric layer 112,and non-linear dielectric 502. The substrate 102, first isolator element104 a, second isolator element 104 b, floating conductive ring 106,dielectric layer 108, non-linear dielectric 110, and dielectric layer112 have been described previously herein in connection with FIGS. 1Aand 1B, and therefore are not described again in detail here.

In the micro-isolator 500 the non-linear dielectric 110 does notentirely fill the space between the first isolator element 104 a and thefloating conductive ring 106. The non-linear dielectric 110 encapsulatesthe first isolator element 104 a and floating conductive ring 106 inthis non-limiting example, however a second non-linear dielectric 502 isincluded between the first isolator element 104 a and the floatingconductive ring 106. The non-linear dielectric 502 may be any suitablenon-linear dielectric. In some embodiments the non-linear dielectric 110and the non-linear dielectric 502 may exhibit similar properties. Insome embodiments, the non-linear dielectric 110 and the non-lineardielectric 502 may exhibit differing non-linear properties. For example,one may be more strongly non-linear than the other in response to anelectric field. One may be more conductive than the other.

FIG. 6 illustrates a cross-sectional view of an alternativemicro-isolator in which the floating conductive ring surrounding theisolator element has a different height than the isolator element. Themicro-isolator 600 comprises substrate 102, first isolator element 104a, second isolator element 104 b, floating conductive ring 606,dielectric layer 108, non-linear dielectric 110, and dielectric layer112. The substrate 102, first isolator element 104 a, second isolatorelement 104 b, dielectric layer 108, non-linear dielectric 110, anddielectric layer 112 have been described previously herein in connectionwith FIGS. 1A and 1B, and therefore are not described again in detailhere.

The floating conductive ring 606 differs from the floating conductivering 106 of FIG. 1A in that its height differs from that of the firstisolator element 104 a. The floating conductive ring 606 has a heightHr, which differs from the height H of the first isolator element 104 a.The height Hr may be selected to simplify fabrication. Filling the gapbetween the first isolator element 104 a and the floating conductivering may be difficult in practice depending on the height H of the firstisolator element 104 a. Making the height Hr less than H may facilitatefilling the gap with the non-linear dielectric 110. The height Hr may beless than 90% of the height H, for example being between 10% and 90% ofthe height H, between 25% and 75% of the height H, less than 10% theheight H, or less than 1% the height H, including any value within thoseranges. As a non-limiting example, H may be 10 microns and Hr may beless than 1 micron, for example being on the order of 10 nanometers. Insome alternative embodiments, Hr may be greater than H.

FIG. 7 illustrates a top view of a micro-isolator having a serpentineisolator element surrounded by a plurality of floating conductive rings,according to a non-limiting embodiment of the present application. Theillustrated serpentine isolator element 702 may be formed of any of thematerials described previously herein in connection with first andsecond isolator elements 104 a and 104 b. The floating conductive rings704 are oval or race-track shaped, and may be formed of any of thematerials described previously herein in connection with floatingconductive ring 106. The number of floating conductive rings 704 is notlimiting. In this non-limiting example, ten floating conductive rings704 are included. The floating conductive rings 704 each surround theserpentine isolator element 702. The floating conductive rings 704 areconcentrically positioned with respect to each other.

FIG. 8 illustrates a top view of a micro-isolator having a segmentedfloating conductive ring surrounding an isolator element, according to anon-limiting embodiment of the present application. The illustratedmicro-isolator comprises isolator element 104 a and segmented floatingconductive ring 802. The isolator element 104 a was described previouslyin connection with FIGS. 1A and 1B, and thus is not described in detailagain here. The segmented floating conductive ring 802 surrounds theisolator element 104 a. The segmented floating conductive ring 802comprises a plurality of segments 804 separated by gaps gr. The numberof segments 804 and the distance of the gaps gr may be selected toprovide a desired level of electric field grading.

While FIG. 8 illustrates an example of a segmented floating conductivering, a further alternative is a ring formed by a plurality of metallicinclusions. That is, in some embodiments, a ring of dielectric materialwith metallic inclusions may be used as a floating conductive ring. Theamount and size of the metallic inclusions may be selected to provide adesired level of electric field grading.

FIG. 9 illustrates a cross-sectional view of a micro-isolator havingfloating conductive rings surrounding both the top and bottom isolatorelements, according to a non-limiting embodiment of the presentapplication. The micro-isolator 900 comprises substrate 102, firstisolator element 104 a, second isolator element 104 b, floatingconductive ring 106, dielectric layer 108, non-linear dielectric 110,dielectric layer 112, and floating conductive ring 902. The substrate102, first isolator element 104 a, second isolator element 104 b,floating conductive ring 106, dielectric layer 108, non-lineardielectric 110, and dielectric layer 112 have been described previouslyherein in connection with FIGS. 1A and 1B, and therefore are notdescribed again in detail here.

The floating conductive ring 902 surrounds the isolator element 104 b.The floating conductive ring 902 may be substantially the same as thefloating conductive ring 106. In some embodiments, however, the floatingconductive ring 902 may be formed of the same material as the isolatorelement 104 b. Thus, in some embodiments, the floating conductive rings106 and 902 are made of different materials.

FIG. 9 shows that the micro-isolator 900 may include electrical accessto the second isolator element 104 b by way of a pad 904 and electricalinterconnect structure 906. In this manner, a center of the secondisolator element 104 b may be electrically contacted even though the pad904 is in the same plane as the second isolator element 104 b.

The micro-isolator 900 also includes an encapsulant 908. The encapsulant908 may be a resin or any other suitable material.

While FIG. 1A illustrates a micro-isolator having a floating conductivering surrounding a top isolator element, and FIG. 9 illustrates anembodiment with floating conductive rings surrounding top and bottomisolator elements, an alternative embodiment of a micro-isolatorincludes a floating conductive ring surrounding a bottom isolatorelement only. In general, it may be desirable to have a floatingconductive ring surrounding the isolator element that receives a highvoltage. In some embodiments, that may be a top isolator element, and insome embodiments it may be a bottom isolator element. Thus, floatingconductive rings of the types described herein may be positioned aroundtop or bottom isolator elements, or both. In some embodiments, amicro-isolator includes two or more isolator elements, with a floatingconductive ring surrounding one or more of them.

An isolator of the types described herein may be deployed in varioussettings to galvanically isolate one portion of an electric circuit fromanother. One such setting is in industrial applications. In someembodiments, an isolator may isolate a motor driver from other portionsof an electric system. The motor driver may operate at voltages equal toor greater than 600V in some embodiments (e.g., up to 3.5 kV or more),and may comprise an inverter to convert a DC signal to an AC signal. Insome embodiments, the motor driver may comprise one or more insulatedgate bipolar transistors (IGBT), and may drive an electric motoraccording to a three-phase configuration.

Another such setting is in photovoltaic systems. In some embodiments, anisolator may be installed in a photovoltaic system to isolate aphotovoltaic panel and/or an inverter from other parts of the system. Insome embodiments, an isolator may be installed between a photovoltaicpanel and an inverter.

Another such setting is in electric vehicles. In some embodiments, anisolator of the types described herein may be used to isolate anysuitable part of an electric vehicle, such as a battery or a motordriver, from other parts of the vehicle.

FIG. 10 is a block diagram illustrating an example of a systemcomprising an isolator of the types described herein. System 1000 maycomprise isolator 1002, low-voltage device 1004, and high-voltage device1006. In some embodiments, low-voltage device 1004 may comprise a deviceoperating at less than 500V. In some embodiments, high-voltage device1006 may comprise a device operating at 500V or higher.

Isolator 1002 may be implemented using micro-isolator 100, 200, 300,400, 500, 600, or 900 and may be disposed between the low-voltage deviceand the high-voltage device. By isolating the two devices from oneanother, a user may be able to physically contact the low-voltage devicewithout being electrically shocked or harmed. Low-voltage device 1004may comprise a user interface unit, such as a computer or other types ofterminals, and/or a communication interface, such as a cable, an antennaor an electronic transceiver. High-voltage device 1006 may comprise amotor driver, an inverter, a battery, a photovoltaic panel, or any othersuitable device operating at 500V or higher. In the embodiments in whichhigh-voltage device 1006 comprises a motor driver, high-voltage device1006 may be connected to an electric motor 1008.

It should be appreciated from the description of FIG. 10 and the typesof micro-isolators described herein that some embodiments of the presentapplication provide an isolated system, comprising: a first deviceconfigured to operate in a first voltage domain; a second deviceconfigured to operate in a second voltage domain; and an isolatorcoupled between the first device and second device and comprising anelectrically floating ring surrounding a first isolator element of apair of vertically separated isolator elements.

The electrically floating ring may be a first electrically floatingring, and the isolated system may further comprise a second electricallyfloating ring surrounding a second isolator element of the pair ofvertically separated isolator elements. In some embodiments, one orboth—when multiple floating conductive rings are provided—are segmentedrings. The electrically floating conductive ring may be shorter than theisolator element it surrounds, in some embodiments. In any suchembodiments, a non-linear dielectric material may encapsulate theisolator element that is surrounded by a floating conductive ring.

Aspects of the present application may provide one or more benefits,some of which have been previously described. Now described are somenon-limiting examples of such benefits. It should be appreciated thatnot all aspects and embodiments necessarily provide all of the benefitsnow described. Further, it should be appreciated that aspects of thepresent application may provide additional benefits to those nowdescribed.

Aspects of the present application provide an isolator capable ofwithstanding voltages exceeding 300V (e.g., 1 kV, 1.5 kV, 2 kV, 2.5 kV,3 kV, and 3.5 kV) while limiting the probability of electric breakdown.As a result of such a reduction in the probability of electricbreakdown, the lifetime of the isolator may be extended.

The terms “approximately” and “about” may be used to mean within ±20% ofa target value in some embodiments, within ±10% of a target value insome embodiments, within ±5% of a target value in some embodiments, andyet within ±2% of a target value in some embodiments. The terms“approximately” and “about” may include the target value.

What is claimed is:
 1. A micro-isolator with enhanced isolationbreakdown voltage, comprising: a first isolator element in a firstplane, wherein the first isolator element comprises a first coil or afirst plate; a second isolator element in a second plane, wherein thesecond isolator element comprises a second coil or a second plate; afirst dielectric material, comprising a polymer, disposed between thefirst and second isolator elements; a first electrically floating ringdisposed in the first plane and surrounding the first isolator element;a second electrically floating ring concentric with the firstelectrically floating ring; and a third electrically floating ringconcentric with the second electrically floating ring, wherein a firstgap distance between the third electrically floating ring and the secondelectrically floating ring differs from a second gap distance betweenthe second electrically floating ring and the first electricallyfloating ring.
 2. The micro-isolator of claim 1, wherein the firstisolator element and the second isolator element are separated in avertical dimension and the first isolator element and the firstelectrically floating ring are separated in a second dimension.
 3. Themicro-isolator of claim 1, further comprising a second dielectricmaterial different than the first dielectric material separating thefirst isolator element from the first electrically floating ring.
 4. Themicro-isolator of claim 3, wherein the second dielectric materialencapsulates the first isolator element.
 5. The micro-isolator of claim1, wherein the first isolator element has a first height, and whereinthe first electrically floating ring has a second height less than thefirst height.
 6. The micro-isolator of claim 1, wherein the firstelectrically floating ring is a segmented ring.
 7. The micro-isolator ofclaim 1, wherein the first isolator element is configured to couple to ahigher voltage than the second isolator element.
 8. A micro-isolatorwith enhanced isolation breakdown voltage, comprising: first and secondisolator elements disposed in respective planes, wherein the firstisolator element comprises a first coil or a first plate and the secondisolator element comprises a second coil or a second plate; a firstdielectric material, comprising a polymer, disposed between the firstand second isolator elements; an electrically floating ring in-planewith and surrounding the first isolator element; and a second dielectricmaterial separating the first isolator element from the electricallyfloating ring, wherein the second dielectric material encapsulates thefirst isolator element but not the electrically floating ring.
 9. Themicro-isolator of claim 8, wherein the electrically floating ring is afirst electrically floating ring, and wherein the micro-isolator furthercomprises a second electrically floating ring concentric with the firstelectrically floating ring.
 10. The micro-isolator of claim 8, whereinthe first isolator element has a first height, and wherein theelectrically floating ring has a second height less than the firstheight.
 11. The micro-isolator of claim 8, wherein the electricallyfloating ring comprises one or more gaps.
 12. The micro-isolator ofclaim 8, wherein the first isolator element is configured to couple to ahigher voltage than the second isolator element.
 13. The micro-isolatorof claim 8, wherein the first isolator element and the second isolatorelement are separated in a vertical dimension and the first isolatorelement and the electrically floating ring are separated in a seconddimension.
 14. A micro-isolator with enhanced isolation breakdownvoltage, comprising: a first isolator element in a first plane,comprising a first coil or a first plate; a second isolator element in asecond plane, comprising a second coil or a second plate; a polymericdielectric material disposed between the first and second isolatorelements; and first, second and third concentric electrically floatingrings surrounding the first isolator element in the first plane; whereina first gap distance between the third electrically floating ring andthe second electrically floating ring differs from a second gap distancebetween the second electrically floating ring and the first electricallyfloating ring.
 15. The micro-isolator of claim 14, wherein the firstisolator element and the second isolator element are separated in avertical dimension and the first isolator element and the firstelectrically floating ring are separated in a second dimension.
 16. Themicro-isolator of claim 14, further comprising a second dielectricmaterial different than the polymeric dielectric material separating thefirst isolator element from the first electrically floating ring. 17.The micro-isolator of claim 16, wherein the second dielectric materialencapsulates the first isolator element.
 18. The micro-isolator of claim14, wherein the first isolator element has a first height, and whereinthe first electrically floating ring has a second height less than thefirst height.
 19. The micro-isolator of claim 14, wherein the firstelectrically floating ring is a segmented ring.
 20. The micro-isolatorof claim 14, wherein the first isolator element is configured to coupleto a higher voltage than the second isolator element.